Isolated this issue down to this mod. having it enabled results in regular, massive lag spikes resulting in the game freezing for half a second or so. these spikes increase in frequency with time until the game becomes unplayable. occurs regardless of map size and/or settings and other mods installed.

looking at my performance tab in Task manager, when these lag spikes occur the CPU usage spikes and GPU usage drops

Hope this makes sense, im happy to clarify further if required